Making Diskette Images without Diskettes

So far we have been preparing boot diskettes by writing to real diskettes. This sounds like the most logical way to do it, but there can be reasons why we want to prepare an image file of a diskette without using real diskettes. Several reasons could be:

• Create a diskette image for a diskette drive you do not have.
• Automate boot image creation (several diskette images for a distribution).
• Create a diskette image for bootable CD-ROM
• Create a diskette image for a PC emulator

Basically we could create a diskette image as follows:

• Create an all zero image file using dd.
• Create a file system onto the image file.
• Mount the image file using the loop option and copy all files to it.
• Install the boot loader onto the image file.

The last part is the trickiest especially for LILO. It's fairly trivial for SYSLINUX and using the device command it can be done with GRUB. There is also another trick for SYSLINUX and GRUB (it does not work with LILO):

• Start with an image file with just the boot loader installed and an empty file system and copy that image file each time you create another image. This image file may be extracted from a real diskette just once.
• Mount the image file using the loop option and copy all files to it.

On Timo's Rescue CD Page there is a good explanation of how to create 2.88MB diskette images for a bootable CD-ROM, using all boot loaders. I could not explain it better. Of course these recipes apply also to other types of disk images.